Radio access bearers (RABs) are specific data flow conduits that identify the service that the Access Stratum (AS) provides to the Non Access Stratum (NAS) in UMTS (Universal Mobile Telecommunications System) for transfer of user data between the User Equipment (UE) and the Core Network (CN). In UMTS, multi Radio Access Bearer (multi-RAB) capability gives the possibility to have two or more simultaneous RABs to support simultaneous communication over the radio access network (RAN) with multiple service access points.
Therefore, in current UTRAN (UMTS Terrestrial Radio Access Network) systems, it is possible to setup a multiRAB connection, having established simultaneously: a CS RAB for a voice call and a PS RAB (or more) to carry the PS data traffic.
RAB Combination allows the radio bearer management to combine different classes of Packet Data Protocol (PDP) context to provide different services simultaneously, e.g. Voice over IP (VoIP) and video streaming. Specific RAB combinations can be too many to list. Following are examples of RAB combination types, for UpLink (UL) and DownLink (DL), specified for CS+PS channels by the standardization group 3GPP in the Technical Report (TR) TR 25.993 “Typical examples of Radio Access Bearers (RABs) and Radio Bearers (RBs) supported by Universal Terrestrial Radio Access (UTRA)”, Release 8.0.0, p.p. 28-287 (section 7.—“Examples of Radio Bearers and Signalling Radio Bearers for FDD”), May 2008.
RAB Combinations of voice+Release 99 PS channel for UL and DL.
Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 32/8Interactive or background/UL: 32 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 0/0Interactive or background/UL: 0 DL: 0 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH (FDD)Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH (FDD)Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 32/32Interactive or background/UL: 32 DL: 32 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH (FDD)Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 32/32 (TTIInteractive or background/UL: 32 DL: 32 kbps/PS RAB20)(20 ms TTI) + UL: 3.4 DL: 3.4 kbps SRBs for DCCH (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 0/07.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 0 DL: 0 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH. (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 8/87.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 8 DL: 8 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH. (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 16/167.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 16 DL: 16 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH. (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 32/327.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 32 DL: 32 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH. (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 64/647.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 64 DL: 64 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH. (FDD)Conversational/speech/UL: (12.2 7.95 5.9 4.75) DL: (12.2Multi-AMR + PS IB 64/1287.95 5.9 4.75) kbps/CS RAB + Interactive or background/UL: 64 DL: 128 kbps/PS RAB + UL: 3.4 DL: 3.4 kbpsSRBs for DCCH. (FDD)Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 32/64Interactive or background/UL: 32 DL: 64 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/64Interactive or background/UL: 64 DL: 64 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/128Interactive or background/UL: 64 DL: 128 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/256Interactive or background/UL: 64 DL: 256 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/384Interactive or background/UL: 64 DL: 384 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/2048Interactive or background/UL: 64 DL: 2048 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 128/2048Interactive or background/UL: 128 DL: 2048 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 128/64Interactive or background/UL: 128 DL: 64 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH.Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 384/64Interactive or background/UL: 384 DL: 64 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps Signalling Radio Bearers forDCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 384/128Interactive or background/UL: 384 DL: 128 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps Signalling Radio Bearers forDCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 384/384Interactive or background/UL: 384 DL: 384 kbps/PSRAB + UL: 3.4 DL: 3.4 kbps Signalling Radio Bearers forDCCHConversational/speech/UL: 5.9 DL: 5.9 kbps/CS RAB +AMR at 5.9 + PS IB 64/64Interactive or background/UL: 64 DL: 64 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 23.85) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 64/64 + SRB#5UL: 64 DL: 64 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 64/128 + SRB#5UL: 64 DL: 128 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 64/384 + SRB#5UL: 64 DL: 384 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 0/0 + SRB#5UL: 0 DL: 0 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 8/8 + SRB#5UL: 8 DL: 8 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 32/32 + SRB#5UL: 32 DL: 32 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 64/256 + SRB#5UL: 64 DL: 256 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Conversational/unknown/PS IB 64/64 + SRB#5UL: 64 DL: 64 kbps/CS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR (max 12.65) +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 32/32 (20 ms) +UL: 32 DL: 32 kbps/PS RAB (20 ms TTI) + UL: 3.4 DL: 3.4 kbpsSRB#5SRBs for DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS S 16/128 + PSStreaming/unknown/UL: 16 DL: 128 kbps/PS RAB +IB 8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS S 128/16 + PSStreaming/unknown/UL: 128 DL: 16 kbps/PS RAB +IB 8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS S 64/16 + PS IBStreaming/unknown/UL: 64 DL: 16 kbps/PS RAB +8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS S 32/256 + PSStreaming/unknown/UL: 32 DL: 256 kbps/PS RAB +IB 8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS S 128/16 + PSStreaming/unknown/UL: 128 DL: 16 kbps/PS RAB +IB 8/8Interactive or background/UL: 8 DL: 8 kbps/PS RAB +(alternative PDU 336 bits)UL: 3.4 DL: 3.4 kbps SRBs for DCCH—AlternativeConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 64/64 + PSInteractive or background/UL: 64 DL: 64 kbps/PS RAB +IB 64/64Interactive or background/UL: 64 DL: 64 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH (FDD)Conversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 0/0 + PS IBInteractive or Background/UL: 0 DL: 0 kbps/PS RAB +0/0Interactive or Background/UL: 0 DL: 0 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: 12.2 DL: 12.2 kbps/CS RAB +AMR + PS IB 0/0 + PS IBInteractive or background/UL: 0 DL: 0 kbps/PS RAB +0/0Interactive or background/UL: 0 DL: 0 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH (L1 multiplexing)Conversational/speech/UL: 5.9 DL: 5.9 kbps/CS RAB +AMR at 5.9 + PS IB 64/64 +Interactive or background/UL: 64 DL: 64 kbps/PS RAB +PS IB 64/64Interactive or background/UL: 64 DL: 64 kbps/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR + PS IB 0/0 + PS8.85 6.6) kbps/CS RAB + Interactive or background/IB 0/0 + SRB#5UL: 0 DL: 0 kbps/PS RAB + Interactive or background/UL: 0 DL: 0 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR + PS IB 64/64 +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 64/64 + SRB#5UL: 64 DL: 64 kbps/PS RAB + Interactive or background/UL: 64 DL: 64 kbps/PS RAB + UL: 3.4 DL: 3.4 kbps SRBsfor DCCH + DL: 0.15 kbps SRB#5 for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR + PS IB 128/128 +8.85 6.6) kbps/CS RAB + Interactive or background/PS IB 128/128 + SRB#5UL: 128 DL: 128 kbps/PS RAB + Interactive orbackground/UL: 128 DL: 128 kbps/PS RAB + UL: 3.4DL: 3.4 kbps SRBs for DCCH + DL: 0.15 kbps SRB#5 forDCCH
RAB Combinations of Voice+(HSDPA Channel in DL and Release 99 PS Channel in UL)
RB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IBCS RAB + Interactive or background/UL: 384 DL: [Bit rate384/HSdepending on the UE category & RAB maximum bit rate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IBCS RAB + Interactive or background/UL: 64 DL: [Bit rate64/HSdepending on the UE category & RAB maximum bit rate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: (12.2 7.95 5.9 4.75)Multi-AMR + PSDL: (12.2 7.95 5.9 4.75) kbps/CS RAB + Interactive orIB 64/HSbackground/UL: 64 DL: [Bit rate depending on the UEcategory & RAB maximum bit rate]/PS RAB + UL: 3.4DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: (12.2 7.95 5.9 4.75)Multi-AMR + PSDL: (12.2 7.95 5.9 4.75) kbps/CS RAB + RB forIB 128/HSInteractive or background/UL: 128 DL: [Bit rate dependingon the UE category & RAB maximum bit rate]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IBCS RAB + RB for Interactive or background/UL: 128 DL:128/HS[Bit rate depending on the UE category & RAB maximumbit rate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: 5.9 DL: 5.9 kbps/CSAMR at 5.9 + PSRAB + RB for Interactive or background/UL: 64 DL: [maxIB 64/HSbit rate depending on the UE category & RAB max. bitrate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR + PS IB8.85 6.6) kbps/CS RAB + Interactive or Background/384/HS + SRB#5UL: 384 DL: [Bit rate depending on the UE category]/PSRAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH + DL: 0.15 kbpsSRB#5 for DCCHRB for Conversational/speech/UL: (12.65 8.85 6.6)WB-AMR + PS IBDL: (12.65 8.85 6.6) kbps/CS RAB + Interactive or64/HS + SRB#5Background/UL: 64 DL: [Bit rate depending on the UEcategory]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCH +DL: 0.15 kbps SRB#5 for DCCHRB for Conversational/speech/UL: 5.9 DL: 5.9 kbps/CSAMR at 5.9 + PSRAB + RB for Interactive or background/UL: 64 DL: [maxIB 64/HS + PS IBbit rate depending on the UE category & RAB max. bitrate]/64/HSPS RAB + RB for Interactive or background/UL: 64DL: [max bit rate depending on the UE category & RABmax. bitrate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IBCS RAB + RB for Interactive or background/UL: 6464/HS + PS IBDL: [max bit rate depending on the UE category & RAB64/HSmax. bitrate]/PS RAB + RB for Interactive or background/UL: 64 DL: [max bit rate depending on the UE category & RABmax. bitrate]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs for DCCHRB for Conversational/speech/UL: (12.65 8.85 6.6)WB-AMR + PS IBDL: (12.65 8.85 6.6) kbps/CS RAB + RB for Interactive or64/HS + PS IB 64/HSBackground/UL: 64 DL: [Bit rate depending on the UEcategory & RAB maximum bit rate]/PS RAB + RB forInteractive or Background/UL: 64 DL: [Bit rate dependingon the UE category & RAB maximum bit rate]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH + DL: 0.15 kbpsSRB#5 for DCCH
RAB Combinations of Voice+(HSDPA Channel in DL and E-DCH-HSUPA-PS Channel in UL)
RB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IB E-CS RAB + Interactive or background/UL: [max bit rateDCH/HSdepending on UE category and TTI] DL: [max bit ratedepending on UE category]/PS RAB + UL: 3.4 DL: 3.4 kbpsSRBs for DCCH on DCHConversational/speech/UL: (5.9, 4.75) DL: (5.9, 4.75)AMR at 5.9, 4.75 +kbps/CS RAB + Interactive or background/UL: [max bitPS IB E-DCH/HSrate depending on UE category and TTI] DL: [max bit ratedepending on UE category]/PS RAB + UL: 3.4 DL: 3.4 kbpsSRBs for DCCH on DCHConversational/speech/UL: (12.65 8.85 6.6) DL: (12.65WB-AMR + PS IB8.85 6.6) kbps/CS RAB + Interactive or background/E-DCH/HS +UL: [max bit rate depending on UE category and TTI] DL:SRB#5[max bit rate depending on UE category]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH on DCH + DL: 0.15 kbpsSRB#5 for DCCHRB for Conversational/speech/UL: (12.2 7.95 5.9 4.75)Multi-AMR + PS IBDL: (12.2 7.95 5.9 4.75) kbps/CS RAB + RB forE-DCH/HS + PSInteractive or background/UL: [max bit rate dependingIB E-DCH/HSon UE category and TTI] DL: [max bit rate depending onUE category]/PS RAB + RB for Interactive orbackground/UL: [max bit rate depending on UEcategory and TTI] DL: [max bit rate depending on UEcategory]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH on DCHRB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IB E-CS RAB + RB for Interactive or background/UL: [max bitDCH/HS + PS IBrate depending on UE category and TTI] DL: [max bit rateE-DCH/HSdepending on UE category]/PS RAB + RB forInteractive or background/UL: [max bit rate dependingon UE category and TTI] DL: [max bit rate depending onUE category]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH on DCHRB for Conversational/speech/UL: (12.65 8.85 6.6)WB-AMR + PS IBDL: (12.65 8.85 6.6) kbps/CS RAB + RB for InteractiveE-DCH/HS + PSor background/UL: [max bit rate depending on UEIB E-DCH/HS +category and TTI] DL: [max bit rate depending on UESRB#5category]/PS RAB + RB for Interactive or background/UL: [max bit rate depending on UE category and TTI] DL:[max bit rate depending on UE category]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH on DCH + DL: 0.15 kbpsSRB#5 for DCCHRB for Conversational/speech/UL: (12.65 8.85 6.6)WB-AMR + PS IBDL: (12.65 8.85 6.6) kbps/CS RAB + RB for InteractiveE-DCH/HS + PSor background/UL: [max bit rate depending on UEIB E-DCH/HScategory and TTI] DL: [max bit rate depending on UEcategory]/PS RAB + RB for Interactive or background/UL: [max bit rate depending on UE category and TTI] DL:[max bit rate depending on UE category]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH on DCHRB for Conversational/speech/UL: 12.2 DL: 12.2 kbps/AMR + PS IB E-CS RAB + RB for Interactive or background/UL: [max bitDCH/HS + PS IBrate depending on UE category and TTI] DL: [max bit rateE-DCH/HS + PSdepending on UE category]/PS RAB + RB forIB E-DCH/HSInteractive or background/UL: [max bit rate dependingon UE category and TTI] DL: [max bit rate depending onUE category]/PS RAB + RB for Interactive orbackground/UL: [max bit rate depending on UEcategory and TTI] DL: [max bit rate depending on UEcategory]/PS RAB + UL: 3.4 DL: 3.4 kbps SRBs forDCCH on DCHRB for Conversational/speech/UL: (12.2 7.95 5.9 4.75)Multi-AMR + PS IBDL: (12.2 7.95 5.9 4.75) kbps/CS RAB + RB forE-DCH/HS + PSInteractive or background/UL: [max bit rate dependingIB E-DCH/HS +on UE category and TTI] DL: [max bit rate depending onPS IB E-DCH/HSUE category]/PS RAB + RB for Interactive orbackground/UL: [max bit rate depending on UEcategory and TTI] DL: [max bit rate depending on UEcategory]/PS RAB + RB for Interactive or background/UL: [max bit rate depending on UE category and TTI] DL:[max bit rate depending on UE category]/PS RAB +UL: 3.4 DL: 3.4 kbps SRBs for DCCH on DCHConversational/speech/UL: 12.2 kbps DL: 12.2 kbps/AMR over HSPA +CS RAB on E-DCH and HS-DSCH + (1, 2 or 3)PS IB E-DCH/HS +Interactive or background/UL: [max bit rate dependingPS IB E-DCH/HS +on UE category and TTI] DL: [max bit rate depending onPS IB E-DCH/HS +UE category]/PS RABs + UL: [max bit rate dependingSRB on E-on UE category and TTI] DL: [max bit rate depending onDCH/DCHUE category] SRBs for DCCH on E-DCH and HS-DSCHConversational/speech/UL: (12.2, 7.95, 5.9, 4.75) kbpsMulti-AMR overDL: (12.2, 7.95, 5.9, 4.75) kbps/CS RAB on E-DCH andHSPA + PS IB E-HS-DSCH + (1, 2 or 3) Interactive or background/UL:DCH/HS + PS IB[max bit rate depending on UE category and TTI] DL:E-DCH/HS + PS[max bit rate depending on UE category]/PS RABs +IB E-DCH/HS +UL: [max bit rate depending on UE category and TTI] DL:SRB on E-[max bit rate depending on UE category] SRBs for DCCHDCH/DCHon E-DCH and HS-DSCHConversational/speech/UL: (5.9, 4.75) kbps DL: (5.9,Multi-AMR4.75) kbps/CS RAB on E-DCH and HS-DSCH + (1, 2 or(5.9, 4.75) over3) Interactive or background/UL: [max bit rateHSPA + PS IB E-depending on UE category and TTI] DL: [max bit rateDCH/HS + PS IBdepending on UE category]/PS RABs + UL: [max bitE-DCH/HS + PSrate depending on UE category and TTI] DL: [max bit rateIB E-DCH/HS +depending on UE category] SRBs for DCCH on E-DCHSRB on E-and HS-DSCHDCH/DCHRB for Conversational/speech/UL: (12.65 8.85 6.6)WB-AMR + PS IBDL: (12.65 8.85 6.6) kbps/CS RAB + RB for InteractiveE-DCH/HS + PSor background/UL: [max bit rate depending on UEIB E-DCH/HS +category and TTI] DL: [max bit rate depending on UEPS IB E-DCH/HScategory]/PS RAB + RB for Interactive or background/UL: [max bit rate depending on UE category and TTI] DL:[max bit rate depending on UE category]/PS RAB + RBfor Interactive or background/UL: [max bit ratedepending on UE category and TTI] DL: [max bit ratedepending on UE category]/PS RAB + UL: 3.4 DL: 3.4 kbpsSRBs for DCCH on DCHConversational/speech/UL: (12.65 8.85 6.6) kbps DL:WB-AMR over(12.65 8.85 6.6) kbps/CS RAB on E-DCH and HS-HSPA + PS IB E-DSCH + (1, 2 or 3) Interactive or background/UL: [maxDCH/HS + PS IBbit rate depending on UE category and TTI] DL: [max bitE-DCH/HS + PSrate depending on UE category]/PS RABs + UL: [maxIB E-DCH/HSbit rate depending on UE category and TTI] DL: [max bitrate depending on UE category] SRBs for DCCH on E-DCH and HS-DSCHE-DCH: Enhanced Dedicated ChannelHSUPA: High Speed Uplink Packet AccessHSDPA: High Speed Downlink Packet Access(WB)-AMR: (Widband-) Adaptive MultiRateIB: Interactive/BackgroundHS: High Speed
A Release 99 downlink channel providing a throughput such as 384 Kbps for MultiRAB is less robust to interference and results in a dropped call rate 20% worse (worse performance) than using 64 Kbps. For uplink case, there is a 40% improvement when using Release 99 instead of using a—HSUPA—high speed channel.
Nowadays, with the increase of the always-on applications in the smartphones, the probability of having a multiRAB connection during a voice call is higher, so the overall voice quality is impacted. In order to mitigate this negative effect, special configurations are used by the operators: for example, mobile network operators configure the use of Release 99 channels for the PS DCH bearer, which has a better performance than the HSPA channels in multiRAB scenarios. The disadvantage of this approach is that the throughput (data bit rate) is impacted (decreased) for the PS service.
Then, a main problem of this multiRAB connection is that the performance is not as good as the single CS voice RAB because the probability of dropped calls in the multiRAB connection is higher than the single RAB. More particularly, the reasons are the following:                Since more than one channel is transmitting at the same time, the power and signal to interference ratio requirements are higher for being able to receive and decode a multiRAB connection than for a single bearer.        Standard signalling traffic in MultiRAB mode is higher than the involved in signalling flow of Single RAB mode and current UTRAN systems are not optimized to handle this MultiRAB signalling with the same performance than in Single RAB mode. All the signalling in MultiRAB goes over the same Signalling Radio Bearer (SRB), which is a radio bearer that carries signalling—typically DownLink Dedicated Control (DCCH)—data channel. If one message is not delivered correctly, then the full channel is dropped.        Parameters for Mobility Management (e.g., handover parameters) in MultiRAB are not optimised by standard specifications. CS+PS session is handled either by the CS or by the PS criteria, but mechanisms to consider MultiRAB as a distinctive entity are not available within standards. This can lead to non-optimised parametrisation of one of the multiple bearers for CS+PS calls in multiRAB mode.        
There is therefore a need to optimise RAB configuration aiming to the best compromise between performance (i.e., call dropping probability or rate of dropped calls) and service throughput (i.e., rate of successful packet delivery) in the cases of CS+PS services over multi-RAB connections in 3G networks.